s390/cio: fix race condition during online processing

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A race condition exists in ccw_device_set_online() that can cause the
online process to fail, leaving the affected device in an inconsistent
state. As a result, subsequent attempts to set that device online fail
with return code ENODEV.

The problem occurs when a path verification request arrives after
a wait for final device state completed, but before the result state
is evaluated.

Fix this by ensuring that the CCW-device lock is held between
determining final state and checking result state.

Note that since:

commit 2297791c92 ("s390/cio: dont unregister subchannel from child-drivers")

path verification requests are much more likely to occur during boot,
resulting in an increased chance of this race condition occurring.

Fixes: 2297791c92 ("s390/cio: dont unregister subchannel from child-drivers")
Reviewed-by: Alexandra Winter <wintera@linux.ibm.com>
Reviewed-by: Vineeth Vijayan <vneethv@linux.ibm.com>
Signed-off-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>

...

This commit is contained in:

Peter Oberparleiter 2024-04-10 11:46:19 +02:00 • committed by Alexander Gordeev

parent 607638faf2

commit 2d8527f2f9

1 changed files with 8 additions and 5 deletions

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drivers/s390/cio/device.c

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